Year	current US$
2000	9.24779943075798
2001	8.91180119366596
2002	9.630467990647166
2003	10.559043329692994
2004	11.760027760024814
2005	12.694766081511151
2006	14.302426774448
2007	16.94291860532492
2008	19.84993367692578
2009	19.936030271671903
2010	21.048583957837835
2011	22.636456407710334
2012	23.201271204642627
2013	25.57054538600268
2014	26.587169373961522
2015	27.01261085225659
2016	26.551003722576702
2017	25.70626557147266
2018	25.436781083164338
2019	26.589611940677372
2020	27.387259482904554
2021	28.26868973091586